Michael Tracey, a journalism professor at the University of Colorado, gave prosecutors hundreds of e-mails from a person now believed to be John Mark Karr. Tracey says he had been communicating with Karr for four years.

Michael Tracey, a journalism professor at the University of Colorado, gave prosecutors hundreds of e-mails from a person now believed to be John Mark Karr. Tracey says he had been communicating with Karr for four years. (Rick Giase / EPA)